Abstract:

【Objective】 High-speed counter-current chromatography (HSCCC) was applied to the isolation and purification of small molecule toxins from metabolites of Beauveria brongniartii (CGMCC No.2382), the pathogenic fungus infecting Dendrolimus tabulaeformis. 【Method】 Ethyl acetate was used to extract toxin components from row extraction of secondary metabolites. The extraction was isolated and purified by HSCCC with two-phase solvent system composed of hexane-ethyl acetate-methanol-water (3.5﹕5﹕3.5﹕5, V/V), and the compounds were identified by GC/MS. The toxicity bioassay was conducted by breeding, epidermis contact and injection. 【Result】 Three compounds, 2-coumaranone,3-methyl-benzoic acid methyl ester and 4-methyl-benzoic acid methyl ester, were obtained with 81%, 89% and 80% in purity by GC method, respectively, from secondary metabolites. The bioassay showed that the toxin 3-methyl-benzoic acid methyl ester resulted the mortality of 34.44% in breeding, 35.56% in epidermis contact and 87.78% in injection. While the toxin 4-methyl-benzoic acid methyl ester caused the mortalities of 37.78%, 38.89% and 91.11%, respectively. 【Conclusion】 3-methyl-benzoic acid methyl ester and 4-methyl-benzoic acid methyl ester are active toxins of Beauveria brongniartii (CGMCC No.2382) to the host insect.

Key words: Beauveria brongniartii, toxin, high-speed counter-current chromatography, Dendrolimus tabulaeformis